What is the domain? $\{2,4,6,8\}$ $\{(5,2),(5,4),(10,6),(15,8)\}$ $\{5,2,4,10,15\}$ $\{5,10,15\}$

Step 1 ：Find the domain of each set:

Step 2 ：Set 1: \(\{2, 4, 6, 8\}\)

Step 3 ：Set 2: \(\{5, 10, 15\}\) (from the x-values of the ordered pairs)

Step 4 ：Set 3: \(\{2, 4, 5, 10, 15\}\)

Step 5 ：Set 4: \(\{5, 10, 15\}\)

Step 6 ：\(\boxed{\text{Final Answer:}}\)

Step 7 ：1. \(\boxed{\{2, 4, 6, 8\}}\)

Step 8 ：2. \(\boxed{\{5, 10, 15\}}\)

Step 9 ：3. \(\boxed{\{2, 4, 5, 10, 15\}}\)

Step 10 ：4. \(\boxed{\{5, 10, 15\}}\)